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Foaming of Microstructured and Nanostructured Polymer Blends

  • Holger RuckdäschelEmail author
  • Peter Gutmann
  • Volker Altstädt
  • Holger Schmalz
  • Axel H. E. Müller
Chapter
Part of the Advances in Polymer Science book series (POLYMER, volume 227)

Abstract

Foaming of multiphase blend systems can be identified as a promising approach to satisfy the steadily growing demand for cellular materials with enhanced properties. However, combining the sophisticated fields of polymer blends and polymer foams not only offers great chances, but also poses a significant challenge, as the multiphase characteristics of blends and the complexity of foam processing need to be taken into account. Therefore, the foaming behavior of polymer blends is systematically analyzed, correlating the blend structure and the physical characteristics of reference systems to their foam processability and resulting foam morphology. The cellular materials are prepared via batch-foam processing, using carbon dioxide as a blowing agent. Starting with an immiscible poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) blend, pathways to tailor the foaming behavior via controlling the micro- and nanostructure of such blends are developed; strategies aiming at reducing the cell size, enhancing the foam homogeneity, and improving the density reduction. As a result of adjusting the blend structure over multiple length scales, cooperative foaming of all blend phases and cell sizes down to several hundred nanometers can be achieved. In the light of the results presented, a general understanding of foaming multiphase blends is developed and guidelines for the selection of blend systems suitable for foaming can be deduced.

Keywords

Blend Foam Morphology Compatibilization Multiphase Nanostructured 

Notes

Acknowledgements

The authors would like to thank all students, technicians, and scientific co-workers contributing to this work, particularly the diploma students Andreas Göldel and Julius Rausch, as well as the lab-technicians Denise Danz and Cornelia Lauble for synthesizing the SBM triblock terpolymers. In addition, BASF SE, Ludwigshafen (Dr. M. Weber), and Mitsubishi Engineering Plastics, Düsseldorf are acknowledged for material support. Financial support by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) within the Collaborative Research Center 481 (SFB 481), project A10 is gratefully acknowledged.

References

  1. 1.
    Gendron R (2005) Thermoplastic foam processing. Principles and development. CRC Press, Boca RatonGoogle Scholar
  2. 2.
    Utracki LA (2002) Polymer blends handbook. Kluwer Academic, New YorkGoogle Scholar
  3. 3.
    Paul DR, Bucknall CB (2000) Polymer blends. Wiley, New YorkGoogle Scholar
  4. 4.
    Spitael P, Macosko CW (2004) Strain hardening in polypropylenes and its role in extrusion foaming. Polym Eng Sci 44:2090–2100CrossRefGoogle Scholar
  5. 5.
    Nam GJ, Yoo JH, Lee JW (2005) Effect of long-chain branches of polypropylene on rheological properties and foam-extrusion performances. J Appl Polym Sci 96:1793–1800CrossRefGoogle Scholar
  6. 6.
    Pham HT, Eiffler J (1995) Blend of branched and linear carbonate polymer resin. US Patent 5,414,027Google Scholar
  7. 7.
    Siripurapu S, Gay YJ, Royer JR, DeSimone JM, Spontak RJ, Khan SA (2002) Generation of microcellular foams of PVDF and its blends using supercritical carbon dioxide in a continuous process. Polymer 43:5511–5520CrossRefGoogle Scholar
  8. 8.
    Liao X, Nawaby AV, Handa YP (2007) Layered and cellular morphologies in atactic/syndiotactic polystyrene blends. Cell Polym 26:69–81Google Scholar
  9. 9.
    Krause B, Diekmann K, van der Vegt NFA, Wessling M (2002) Open nanoporous morphologies from polymeric blends by carbon dioxide foaming. Macromolecules 35:1738–1745CrossRefGoogle Scholar
  10. 10.
    Klempner D, Frisch KC (1999) Handbook of polymeric foams and foam technology. Hanser, MunichGoogle Scholar
  11. 11.
    Doroudiani S, Park CB, Kortschot MT (1998) Processing and characterization of microcellular foamed high-density polyethylene/isotactic polypropylene blends. Polym Eng Sci 38:1205–1215CrossRefGoogle Scholar
  12. 12.
    Huang HX, Wang JK (2007) Improving polypropylene microcellular foaming through blending and the addition of nano-clacium carbonate. J Appl Polym Sci 106:505–513CrossRefGoogle Scholar
  13. 13.
    Rachtanapun P, Selke SEM, Matuana LM (2003) Microcellular foam of polymer blends of HDPE/PP and their composites with wood fiber. J Appl Polym Sci 88:2842–2850CrossRefGoogle Scholar
  14. 14.
    Zhang P, Zhou NQ, Wu QF, Wang MY, Peng XF (2007) Microcellular foaming of PE/PP blends. J Appl Polym Sci 104:4149–4159CrossRefGoogle Scholar
  15. 15.
    Ramesh NS, Rasmussen DH, Campbell GA (1994) The heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass-transition particles. 1. Mathematical-modeling and numerical-simulation. Polym Eng Sci 34:1685–1697CrossRefGoogle Scholar
  16. 16.
    Ramesh NS, Rasmussen DH, Campbell GA (1994) The heterogeneous nucleation of microcellular foams assisted by the survival of microvoids in polymers containing low glass-transition particles. 2. Experimental results and discussion. Polym Eng Sci 34:1698–1706CrossRefGoogle Scholar
  17. 17.
    Campbell GA, Rasmussen DH (1994) Controlling heterogeneous nucleation and growth of foams. US Patent 5,358,675Google Scholar
  18. 18.
    Campbell GA, Rasmussen DH (1994) Controlling heterogeneous nucleation and growth of foams. US Patent 5,369,135Google Scholar
  19. 19.
    Spitael P, Macosko CW, McClurg RB (2004) Block copolymer micelles for nucleation of microcellular thermoplastic foams. Macromolecules 37:6874–6882CrossRefGoogle Scholar
  20. 20.
    Han XM, Lee LJ, Tomasko DL (2005) CO2 foaming of polymer nanocomposite blends. Aust J Chem 58:492–503CrossRefGoogle Scholar
  21. 21.
    Han XM, Shen J, Huang HX, Tomasko DL, Lee LJ (2007) CO2 foaming based on polystyrene/poly(methyl methacrylate) blend and nanoclay. Polym Eng Sci 47:103–111CrossRefGoogle Scholar
  22. 22.
    Rogers J-V, Kisner RD (1993) Ultra low density polyolefin foam, foamable polyolefin compositions and process for making same. US Patent 5,290,822Google Scholar
  23. 23.
    Smith PJ, Cross BJ (1996) Foamed articles of styrenic and acrylic polymers blend. US Patent 6,063,485Google Scholar
  24. 24.
    Park CB, Padareva V, Lee PC, Naguib HE (2005) Extruded open-celled LDPE-based foams using non-homogeneous melt structure. J Polym Eng 25:239–260CrossRefGoogle Scholar
  25. 25.
    Wong CM, Tsai SJ, Ying CH, Hung ML (2006) Effect of low density polyethylene on polystyrene foam. J Cell Plast 42:153–163CrossRefGoogle Scholar
  26. 26.
    Lee H, Mall S, He P, Shi DL, Narasimhadevara S, Yeo-Heung Y, Shanov V, Schulz MJ (2007) Characterization of carbon nanotube/nanofiber-reinforced polymer composites using an instrumented indentation technique. Composites Part B 38:58–65CrossRefGoogle Scholar
  27. 27.
    Tashiro H, Naito H, Takayama M, Yoshimura I (1983) Fluid transmitting polyolefin foams and method of making the same. US Patent 4,384,032Google Scholar
  28. 28.
    Barry JJA, Nazhat SN, Rose FRAJ, Hainsworth AH, Scotchford CA, Howdle SM (2005) Supercritical carbon dioxide foaming of elastomer/heterocyclic methacrylate blends as scaffolds for tissue engineering. J Mater Chem 15:4881–4888CrossRefGoogle Scholar
  29. 29.
    Reichelt N, Stadlbauer M, Folland R, Park CB, Wang J (2003) PP-blends with tailored foamability and mechanical properties. Cell Polym 22:315–327Google Scholar
  30. 30.
    Diaf A, Enick RM, Beckman EJ (1993) Molecular redesign of expanded polystyrene to allow use of carbon-dioxide as a foaming agent. 1. Reversible binding of CO2. J Appl Sci 50:835–844CrossRefGoogle Scholar
  31. 31.
    Sarbu T, Styranec TJ, Beckman EJ (2000) Design and synthesis of low cost, sustainable CO2-philes. Ind Eng Chem Res 39:4678–4683CrossRefGoogle Scholar
  32. 32.
    Vachon C, Tatibouet J (2004) Effect of additives on the solubility and diffusivity of carbon dioxide in polystyrene. AntecGoogle Scholar
  33. 33.
    Sun HL, Mark JE, Tan SC, Venkatasubramanian N, Houtz MD, Arnold FE, Lee CYC (2005) Microcellular foams from some high-performance composites. Polymer 46:6623–6632CrossRefGoogle Scholar
  34. 34.
    Tan SC, Bai Z, Sun H, Mark JE, Arnold FE, Lee CYC (2003) Processing of microcellular foams from polybenzobisthiazole/polyetherketoneketone molecular composites. J Mater Sci 38:4013–4019CrossRefGoogle Scholar
  35. 35.
    Takeda N (1989) Foams of polyolefin/polystyrene resin mixture. US Patent 4,847,150Google Scholar
  36. 36.
    Park CB, Baldwin DF, Suh NP (1995) Effect of the pressure drip rate on cell nucleation in continuous processing of microcellular polymers. Polym Eng Sci 35:432–440CrossRefGoogle Scholar
  37. 37.
    Sahagun CZ, Gonzalez-Nunez R, Rodrigue D (2006) Morphology of extruded PP/HDPE foam blends. J Cell Plast 42:469–485CrossRefGoogle Scholar
  38. 38.
    Wollecke F (2005) Korrelation dehnrheologischer Kenngrößen mit dem Schäumverhalten von Polymeren, University of Bayreuth, ISBN 3–930400–35–9Google Scholar
  39. 39.
    Werner P, Verdejo R, Wöllecke F, Altstädt V, Sandler JKW, Shaffer MSP (2005) Carbon nanofibers allow foaming of semicrystalline poly(ether ether ketone). Adv Mater 17:2864–2869CrossRefGoogle Scholar
  40. 40.
    Nam PH, Maiti P, Okamoto M, Kotaka T, Nakayama T, Takada M, Ohshima M, Usuki A, Hasegawa N, Okamoto H (2002) Foam processing and cellular structure of polypropylene/clay nanocomposites. Polym Eng Sci 42:1907–1918CrossRefGoogle Scholar
  41. 41.
    Kressler J, Kammer HW (1987) Miscibility behavior of poly(2,6-dimethylphenylene oxide) and poly(styrene-co-acrylonitrile). Acta Polym 38: 600–602CrossRefGoogle Scholar
  42. 42.
    Merfeld GD, Karim A, Majumdar B, Satija SK, Paul DR (1998) Interfacial thickness in bilayers of poly(phenylene oxide) and styrenic copolymers. J Polym Sci B Polym Phys 36:3115–3125CrossRefGoogle Scholar
  43. 43.
    Potente H, Bastian M, Bergemann K, Senge M, Scheel G, Winkelmann T (2001) Morphology of polymer blends in the melting section of co-rotating twin screw extruders. Polym Eng Sci 41:222–231CrossRefGoogle Scholar
  44. 44.
    Sundararaj U, Macosko CW (1995) Drop breakup and coalescence in polymer blends – the effect of concentration and compatibilization. Macromolecules 28:2647–2657CrossRefGoogle Scholar
  45. 45.
    Ruckdäschel H, Sandler JKW, Altstädt V, Rettig C, Schmalz H, Abetz V, Müller AHE (2006) Compatibilization of PPE/SAN blends by triblock terpolymers: correlation between block terpolymer composition, morphology and properties. Polymer 47:2772–2790CrossRefGoogle Scholar
  46. 46.
    Utracki LA (1991) On the viscosity-concentration dependence of immiscible polymer blends. J Rheol 35:1615–1637CrossRefGoogle Scholar
  47. 47.
    Ruckdäschel H, Rausch J, Sandler JKW, Altstädt V, Schmalz H, Müller AHE (2008) Correlation of the melt rheological properties with the foaming behavior of immiscible blends of poly(2,6-dimethyl-1,4-phenylene ether) and poly(styrene-co-acrylonitrile). Polym Eng Sci 48:2111–2125CrossRefGoogle Scholar
  48. 48.
    Le Meins JF, Moldenaers P, Mewis J (2002) Suspensions in polymer melts. 1. Effect of particle size on the shear flow behavior. Ind Eng Chem Res 41:6297–6304CrossRefGoogle Scholar
  49. 49.
    Le Meins JF, Moldenaers P, Mewis J (2003) Suspensions of monodisperse spheres in polymer melts: particle size effects in extensional flow. Rheol Acta 42:184–190CrossRefGoogle Scholar
  50. 50.
    Van Puyvelde P, Velankar S, Moldenaers P (2001) Rheology and morphology of compatibilized polymer blends. Curr Opin Colloid Interface Sci 6:457–463CrossRefGoogle Scholar
  51. 51.
    Krishnamoorti R, Giannelis EP (1997) Rheology of end-tethered polymer layered silicate nanocomposites. Macromolecules 30:4097–4102CrossRefGoogle Scholar
  52. 52.
    Jiang L, Lam YC, Tam KC, Chua TH, Sim GW, Ang LS (2005) Strengthening acrylonitrile-butadiene-styrene (ABS) with nano-sized and micron-sized calcium carbonate. Polymer 46:243–252CrossRefGoogle Scholar
  53. 53.
    Wu G, Asai S, Sumita M, Hattori T, Higuchi R, Washiyama J (2000) Estimation of flocculation structure in filled polymer composites by dynamic rheological measurements. Colloid Polym Sci 278:220–228CrossRefGoogle Scholar
  54. 54.
    Chern RT, Sheu FR, Jia L, Stannett VT, Hopfenberg HB (1987) Transport of gases in unmodified and arylbrominated 2,6-dimethyl-1,4-poly (phenylene oxide). J Membr Sci 35:103–115CrossRefGoogle Scholar
  55. 55.
    Nawaby AV, Handa YP, Liao X, Yoshitaka Y, Tomohiro M (2007) Polymer-CO2 systems exhibiting retrograde behavior and formation of nanofoams. Polym Int 56:67–73CrossRefGoogle Scholar
  56. 56.
    Lee ST (2000) Foam extrusion. Principles and practice. Technomic Publishing Company, LancasterCrossRefGoogle Scholar
  57. 57.
    Wagner MH, Bernnat A, Schulze V (1998) The rheology of the rheotens test. J Rheol 42: 917–928CrossRefGoogle Scholar
  58. 58.
    McInerney LF, Kao N, Bhattacharya SN (2003) Melt strength and extensibility of talc-filled polypropylene. Polym Eng Sci 43:1821–1829CrossRefGoogle Scholar
  59. 59.
    Krieger IM (1963) A dimensional approach to colloid rheology. Trans Soc Rheol 7:101–109CrossRefGoogle Scholar
  60. 60.
    Seong DG, Kang TJ, Youn JR (2005) Rheological characterization of polymer-based nanocomposites with different nanoscale dispersions. e-Polymers 5Google Scholar
  61. 61.
    Milner ST, Xi HW (1996) How copolymers promote mixing of immiscible homopolymers. J Rheol 40:663–687CrossRefGoogle Scholar
  62. 62.
    Creton C, Kramer EJ, Hadziioannou G (1991) Critical molecular-weight for block copolymer reinforcement of interfaces in a 2-phase polymer blend. Macromolecules 24:1846–1853CrossRefGoogle Scholar
  63. 63.
    Creton C, Kramer EJ, Hui CY, Brown HR (1992) Failure mechanisms of polymer interfaces reinforced with block copolymers. Macromolecules 25:3075–3088CrossRefGoogle Scholar
  64. 64.
    Gottschalk A, Muhlbach K, Seitz F, Stadler R, Auschra C (1994) Blends of poly(2,6-dimethyl-1,4-phenylene oxide) with styrene copolymers. Macromol Symp 83:127–146CrossRefGoogle Scholar
  65. 65.
    Auschra C, Stadler R (1993) New ordered morphologies in ABC triblock copolymers. Macromolecules 26:2171–2174CrossRefGoogle Scholar
  66. 66.
    Auschra C, Stadler R (1993) Thermal-stability of poly(styrene-b-methyl methacrylate) and poly(styrene-b-ethylene-co-1-butene-b-methyl methacrylate) – a gel-permation. Polym Bull 30:305–311CrossRefGoogle Scholar
  67. 67.
    Brown HR, Krappe U, Stadler R (1996) Effect of ABC triblock copolymers with an elastomeric midblock on the adhesion between immiscible polymers. Macromolecules 29:6582–6588CrossRefGoogle Scholar
  68. 68.
    Auschra C, Stadler R (1993) Polymer alloys based on poly(2,6-dimethyl-1,4-phenylene ether) and poly(styrene-co-acrylonitrile) using poly(styrene-b-(ethylene-co-butylene)-b-methyl methacrylate) triblock copolymers as compatibilizers. Macromolecules 26:6364–6377CrossRefGoogle Scholar
  69. 69.
    Ruckdäschel H, Sandler JKW, Altstädt V, Schmalz H, Abetz V, Müller AHE (2007) Toughening of immiscible PPE/SAN blends by triblock terpolymers. Polymer 48:2700–2719CrossRefGoogle Scholar
  70. 70.
    Ruckdäschel H, Gutmann P, Altstädt V, Schmalz H, Müller AHE. Cellular polymer blends with nanostructured cell walls. Macromolecules, submittedGoogle Scholar
  71. 71.
    Quintens D, Groeninckx G, Guest M, Aerts L (1991) Viscoelastic properties related to the phase morphology of 60/40 Pc/San blend. Polym Eng Sci 31:1207–1214CrossRefGoogle Scholar
  72. 72.
    Van Krevelen DW (1976) Properties of polymers. Elsevier, AmsterdamGoogle Scholar
  73. 73.
    Ruckdäschel H, Rausch J, Sandler JKW, Altstädt V, Schmalz H, Müller AHE (2007) Foaming of miscible and immiscible polymer blends. Mater Res Soc Symp Proc 977Google Scholar
  74. 74.
    Chiou JS, Paul DR (1987) Gas permeation in miscible homopolymer copolymer blends. 1.Poly(methyl methacrylate) and styrene acrylonitrile copolymers. J Appl Polym Sci 34:1037–1056CrossRefGoogle Scholar
  75. 75.
    Chow TS (1980) Macromolecular interpretation of the glass-transition temperature of polymer-diluent systems. Macromolecules 13:362–364CrossRefGoogle Scholar
  76. 76.
    Suess M, Kressler J, Kammer HW (1987) The miscibility window of poly(methyl methacrylate) poly(styrene-co-acrylonitrile) blends. Polymer 28:957–960CrossRefGoogle Scholar
  77. 77.
    Couchman PR (1987) Thermodynamics and the compositional variation of glass-transition temperatures. Macromolecules 11:1156–1161CrossRefGoogle Scholar
  78. 78.
    Taki K, Nitta K, Kihara S, Ohshima M (2005) CO2 foaming of poly(ethylene glycol)/ polystyrene blends: relationship of the blend morphology, CO2 mass transfer, and cellular structure. J Appl Polym Sci 97:1899–1906CrossRefGoogle Scholar
  79. 79.
    Shen J, Han XM, Lee LJ (2006) Nanoscaled reinforcement of polystyrene foams using carbon nanofibers. J Cell Plast 42:105–126CrossRefGoogle Scholar
  80. 80.
    Colton JS, Suh NP (1987) The nucleation of microcellular thermoplastic foam with additives.1. Theoretical considerations. Polym Eng Sci 27:485–492CrossRefGoogle Scholar
  81. 81.
    Tomasko DL, Han XM, Liu DH, Gao WH (2003) Supercritical fluid applications in polymer nanocomposites. Curr Opin Solid State Mater Sci 7:407–412CrossRefGoogle Scholar
  82. 82.
    Tomasko DL, Li HB, Liu DH, Han XM, Wingert MJ, Lee LJ, Koelling KW (2003) A review of CO2 applications in the processing of polymers. Ind Eng Chem Res 42:6431–6456CrossRefGoogle Scholar
  83. 83.
    Grace HP (1982) Dispersion phenomena in high-viscosity immiscible fluid systems and application of static mixers as dispersion devices in such systems. Chem Eng Commun 14:225–277CrossRefGoogle Scholar
  84. 84.
    Ruckdäschel H, Altstädt V, Müller AHE (2007) Foaming of polymer blends – chance and challenge. Cell Polym 26:367–380Google Scholar
  85. 85.
    Kolarik J, Lednicky F, Locati G, Fambri L (1997) Ultimate properties of polycarbonate blends: effects of inclusion plastic deformation and of matrix phase continuity. Polym Eng Sci 37:128–137CrossRefGoogle Scholar
  86. 86.
    Harrats C, Thomas S, Groeninckx G (ed) Micro- and nanostructured multiphase polymer blend systems: phase morphology and interfaces. CRC Press, Boca RatonGoogle Scholar
  87. 87.
    Steinmann S, Gronski W, Friedrich C (2001) Cocontinuous polymer blends: influence of viscosity and elasticity ratios of the constituent polymers on phase inversion. Polymer 42:6619–6629CrossRefGoogle Scholar
  88. 88.
    Marin N, Favis BD (2002) Co-continuous morphology development in partially miscible PMMA/PC blends. Polymer 43:4723–4731CrossRefGoogle Scholar
  89. 89.
    Pötschke P, Paul DR (2003) Formation of co-continuous structures in melt-mixed immiscible polymer blends. J Macromol Sci Polym Rev C43:87–141CrossRefGoogle Scholar
  90. 90.
    Willemse RC (1999) Co-continuous morphologies in polymer blends: stability. Polymer 40:2175–2178CrossRefGoogle Scholar
  91. 91.
    Tol RT, Groeninckx G, Vinckier I, Moldenaers P, Mewis J (2004) Phase morphology and stability of co-continuous (PPE/PS)/PA6 and PS/PA6 blends: effect of rheology and reactive compatibilization. Polymer 45:2587–2601CrossRefGoogle Scholar
  92. 92.
    Everaert V, Aerts L, Groeninckx G (1999) Phase morphology development in immiscible PP/(PS/PPE) blends influence of the melt-viscosity ratio and blend composition. Polymer 40:6627–6644CrossRefGoogle Scholar
  93. 93.
    Göldel A, Ruckdäschel H, Müller AHE, Pötschke P, Altstädt V (2008) Controlling the phase morphology of immiscible poly(2,6-dimethyl-1,4-phenylene ether)/poly(styrene-co-acrylonitrile) blends via addition of polystyrene. e-Polymers 151Google Scholar
  94. 94.
    Gutmann P, Ruckdäschel H, Bangarusampath DS, Altstädt V, Schmalz H, Müller AHE (2009) Influence of the microstructure on the foaming behavior of an immiscible blend system. AntecGoogle Scholar
  95. 95.
    Palierne JF (1990) Linear rheology of viscoelastic emulsions with interfacial-tension. Rheol Acta 29:204–214CrossRefGoogle Scholar
  96. 96.
    Pötschke P, Fornes TD, Paul DR. (2002) Rheological behavior of multiwalled carbon nanotube/polycarbonate composites. Polymer 43:3247–3255CrossRefGoogle Scholar
  97. 97.
    Abdel-Goad M, Pötschke P (2005) Rheological characterization of melt processed polycarbonate-multiwalled carbon nanotube composites. J Non-Newtonian Fluid Mech 128:2–6CrossRefGoogle Scholar
  98. 98.
    Daigneault LE, Gendron R (2001) Blends of CO2 and 2-ethyl hexanol as replacement foaming agents for extruded polystyrene. J Cell Plast 37:262–272CrossRefGoogle Scholar
  99. 99.
    Gendron R, Champagne MF, Delaviz Y, Polasky ME (2006) Foaming polystyrene with a mixture of CO2 and ethanol. J Cell Plast 42:127–138CrossRefGoogle Scholar
  100. 100.
    Gutmann P, Hildebrandt K, Altstädt V, Müller AHE (2009) Foaming of an immiscible blend system using organic liquids as blowing agents. RapraGoogle Scholar

Copyright information

© Springer 2009

Authors and Affiliations

  • Holger Ruckdäschel
    • 1
    Email author
  • Peter Gutmann
    • 1
  • Volker Altstädt
    • 1
  • Holger Schmalz
    • 1
  • Axel H. E. Müller
    • 1
  1. 1.Department of Polymer EngineeringUniversity of BayreuthBayreuthGermany

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